System and method for generating unique sector identifiers for an identificationless disk format

Abstract

A method and apparatus for determining the position of a head with respect to a rotating magnetic disk within a disk data storage device using standard signals output from a head/drive assembly (HDA). Servo zone detect pulses are used to determine the position of the read/write head with respect to the servo cells. An index pulse determines the angular position of the head. A servo zone counter is incremented by one in response to a servo zone detect pulse. Accordingly, the servo zone counter maintains a unique value which is corresponds to each data wedge on a surface of the disk. A servo clock has a constant number of cycles between sectors. The servo clock is coupled to the clock input of a sector counter. A sector pulse is generated and the sector counter is reset to zero when the number of cycles counted indicates that the beginning of a sector is under the read/write head. A sector ID counter counts the number of sector pulses. The output of the sector ID counter is equal to the sector ID of the sector which the read/write head is currently over. Thus, the data stored in the memory allows the present invention to determine the sector ID of the sector that the read/write head is over. Since the sector ID can be determined without being stored on the disk, at least some of the information which is normally recorded on the surface of the disk (i.e., the sector ID and associated fields) may be removed from the disk surface leaving additional room to store data.

We claim: 
     
       1. A method for outputting a unique sector identification associated with each sector on a rotating data storage medium having a plurality of servo zones within a data storage device, wherein (1) at least one sector for storing data is positioned between adjacent servo zones to define a data wedge, (2) a non-integer number of sectors are selectably be positioned within a data wedge, and (3) the servo zones and sectors lack an embedded sector identifier, the method comprising the steps of: (a) initializing a servo zone count value in response to receipt of an index servo zone detect pulse generated when a read/write head is proximate an index servo zone, such that each servo zone count value defines a unique value corresponding to one of such servo zones;   (b) changing the servo zone count value in response to receipt of each next servo zone detect pulse generated when the read/write head is proximate each next servo zone;   (c) for each servo zone count value, retrieving predetermined values for: (1) a first length value defining a distance from a current servo zone to a fixed position within a first sector within a current data wedge;   (2) at least one next length value defining a distance from a fixed position within a current sector within a current data wedge to a fixed position within a next sector within such current data wedge;   (3) a sector identification value defining a unique identifier for such first sector:     (d) changing a sector count value in response to a received servo clock;   (e) outputting a sector pulse when the changes in the sector count value equal the retrieved first length value, such sector pulse thereby indicating a fixed position within such first sector after such current servo zone;   (f) outputting a next sector pulse when the changes in the sector count value equal each retrieved next length value, each such next sector pulse thereby indicating a fixed position within a next sector within such current data wedge;   (g) repeating step (f) until a next servo zone detect pulse is received;   (h) initializing a sector identification count value to the retrieved sector identification value;   (i) changing the sector identification count value in response to each sector pulse output within a current data wedge, whereby each sector within such data wedge is uniquely identifiable by a corresponding sector identification count value.   
     
     
       2. The method of claim 1, wherein the first sector of a current data wedge may be spaced any desired distance from a current servo zone. 
     
     
       3. The method of claim 1, including the further steps of: (a) for each servo zone count value, retrieving predetermined values for: (1) a sector tally value defining the number of sectors in a current data wedge;   (2) a servo split value defining the number of servo clocks occurring from a fixed location within the last sector in such current data wedge to a fixed position within the next servo zone;     (b) changing a sector tally count value in response to each sector pulse output within a current data wedge,   (c) changing a servo split count in response to the servo clock, commencing when the changes in the sector tally count value equal the retrieved sector tally value;   (d) indicating the end of the last sector in the current data wedge when the changes in the servo split count equal the retrieved servo split value.   
     
     
       4. The method of claim 1, further including the step of applying a servo zone windowing assembly to determine whether each received servo zone detect pulse is valid. 
     
     
       5. The method of claim 1, further including the step of applying an index servo zone detect pulse windowing assembly to determine whether each received index servo zone detect pulse is valid. 
     
     
       6. A system for defining a unique sector identification associated with each sector on a rotating data storage medium having a plurality of servo zones within a data storage device, wherein (1) at least one sector for storing data is positioned between adjacent servo zones to define a data wedge, (2) a non-integer number of sectors are selectively be positioned within a data wedge, and (3) the servo zones and sectors lack an embedded sector identifier, the system including: (a) a servo zone counter having a servo zone count value initialized in response to receipt of an index servo zone detect pulse generated when a read/write head is proximate an index servo zone, such that each servo zone count value defines a unique value corresponding to one of such servo zones, the servo zone count value being changed in response to receipt of each next servo zone detect pulse generated when the read/write head is proximate each next servo zone;   (b) storage means, coupled to the servo zone counter, for storing, for each servo zone count value, predetermined values for: (1) a first length value defining a distance from a current servo zone to a fixed position within a first sector within a current data wedge;   (2) at least one next length value defining a distance from a fixed position within a current sector within a current data wedge to a fixed position within a next sector within such current data wedge;   (3) a sector identification value defining a unique identifier for such first sector;     (c) a sector counter, coupled to the storage means, having a sector count value that is changed in response to a received servo clock, and which outputs a sector pulse when the changes in the sector count value equal (1) the first length value for a current servo zone count value, such sector pulse thereby indicating a fixed position within such first sector after such current servo zone, and (2) each next length value for a current servo zone count value, each such next sector pulse thereby indicating a fixed position within a next sector within such current data wedge;   (d) a sector identification counter, coupled to the storage means and the sector counter, having a sector identification count value initialized to the sector identification value for a current servo zone count value, such sector identification count value being changed in response to each sector pulse output within a current data wedge, whereby each sector within such data wedge is uniquely identifiable by a corresponding sector identification count value.   
     
     
       7. The system of claim 6, wherein the first sector of a current data wedge may be spaced any desired distance from a current servo zone. 
     
     
       8. The system of claim 6, further including: (a) storage means, coupled to the servo zone counter, for storing, for each servo zone count value, predetermined values for: (1) a sector tally value defining the number of sectors in a current data wedge;   (2) a servo split value defining the number of servo clocks occurring from a fixed location within the last sector in such current data wedge to a fixed position within the next servo zone;     (b) a sector tally counter, coupled to the storage means, having a sector tally count that is changed in response to each sector pulse output within a current data wedge,   (c) a servo split counter, coupled to the storage means and the sector tally counter, having a servo split count that changes in response to a received servo clock, commencing when the changes in the sector tally count value equal the sector tally value, and which indicates the end of the last sector in the current data wedge when the changes in the servo split count equal the servo split value.   
     
     
       9. The system of claim 6, further including a servo zone windowing assembly to determine whether each received servo zone detect pulse is valid. 
     
     
       10. The system of claim 6, further including an index servo zone detect pulse windowing assembly to determine whether each received index servo zone detect pulse is valid.